Three people were injured in an explosion in Ukraine’s rebel stronghold Donetsk on Saturday, including a candidate for the post of the self-proclaimed republic’s leader.

The incident took place just four weeks after the head of the Donetsk People’s Republic (DPR) Alexander Zakharchenko was killed in a bombing at a cafe in broad daylight.

Saturday’s explosion happened near the local communist party’s offices as the last participants of a party congress were leaving the building, a DPR police officer told an AFP correspondent at the scene.

Igor Khakimzyanov, the party’s candidate for the post of the DPR leader, was among the wounded.

“According to some reports, Igor Khakimzyanov suffered burns when he was collecting signatures near the entrance,” Boris Litvinov, the 64-year-old head of the communist party said.

The place was immediately cordoned off by men in military fatigues.

The case is being handled by the DPR’s ministry of state security.

Zakharchenko, the 42-year-old head of the self-proclaimed DPR, was killed on August 31, with the rebels planning to hold a leadership election on November 11.

More than 10,000 people have been killed since the rebel insurgency broke out in the eastern Donetsk and Lugansk regions in April 2014 following Russia’s annexation of Crimea from Ukraine.

Kiev and its Western allies accuse Russia of funnelling troops and arms across the border.

Moscow has denied the allegations despite evidence it has been involved in the fighting.